WASHINGTON, July 8 (UPI) -- Sen. Robert Menendez has asked the Department of Justice to launch an investigation into claims that the Cuban government attempted to derail his political career through a trumped up prostitution scandal.

Menendez, D-N.J., sent a letter to officials in April asking investigators to pursue evidence from the CIA that Cuban agents had been credibly linked to 2012 allegations that he had visited underage prostitutes. The son of Cuban immigrants, Menendez also holds the gavel in the powerful Senate Foreign Relations Committee and is one of Washington's most ardent critics of former Cuban President Fidel Castro and his regime.

The letter from Menendez's attorney, Stephen M. Ryan, has not been made public, but sources briefed the the Washington Post on the nature of its contents and the intelligence information to which it pertains.

U.S. agents discovered the information against Menendez came from a fake tipster, going by the name "Pete Williams," created by Cuba's Directorate of Intelligence. "Williams" told FBI agents he had evidence of Menendez attending parties at the Dominican Republic home of Salomon Melgen, a doctor and friend of the senator, where underage prostitutes were present.

Allegations against Menendez were first published on the Daily Caller website in November 2012, with claims from two Dominican women who said the senator had paid them for sex. The FBI was unable to corroborate those claims, and last year, the women recanted their story.

The FBI is separately pursing an investigation into Menendez to determine if he inappropriately exerted his influence on Melgen's behalf. Menendez twice disputed claims that Melgen overbilled Medicare for eye treatments by $8.9 million and pressed State and Commerce officials to lean on Dominican Republic officials to enforce a port security contract involving a company of which Melgen partly owned.

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